Treatment modality and outcomes among early-stage non-small cell lung cancer patients with COPD: a cohort study - Kang, Noeul; Shin, Sun Hye; Noh, Jae Myoung; Kang, Danbee; Kim, Hojoong; Kwon, O Jung; Pyo, Hongryull; Ahn, Yong Chan; Kim, Hong Kwan; Choi, Yong Soo; Kim, Jhingook; Zo, Jae Ill; et al. (Journal of Thoracic Disease, 2020)